Predetermined torque release wrench



5 Sheets-Sheet 1 Filed Oct. 8, 1952 INVENTOR PAUL OLZAG/VON ATTORN EY5 June 12, 1956 P. OLLAGNON 2,749,786

PREDETERMINED TORQUE RELEASE WRENCH Filed Oct. 8, 1952 3 Sheets-Sheet 2 l.'. 7 V U V V v 0 0.0.0.0.0.0.0. 0.0.0.0 .0.0. 0 0 0 0 0.0.

INVENTOR: PAUL 0LlAG/V0/V BY WW, 0% M M ATTORNEYS- June 12, 1956 P. OLLAGNON PREDETERMINED TORQUE RELEASE WRENCH 3 Sheets-Sheet 3 Filed Oct. 8. 1952 INVENTOR: PA UL 0L LAG/VON ATTORNEYS- United States Patent PREDETERMINED TORQUE RELEASE WRENCH Paul Ollagnon, Saint-Etienne, France, assignor to Societe Anonyme des Forges Stephanoises, Saint-Etienne (Loire), France Application October 8, 1952, Serial No. 313,645

Claims priority, application France October 26, 1951 8 Claims. (Cl. 81-525) My invention relates to a predetermined torque release wrench of the type including a shank and a yielding elongated bar secured to the operative end thereof and extending inside a longitudinal groove of the shank. When acting on the handle forming the end of said yielding bar, the latter moves away from the shank as soon as the stress exerted on the nut or screw engaged by the operative end of said shank rises beyond a predetermined value.

My invention has for its object improved means for clamping the shank and bar together at a predetermined point of their length so as to define the free operative length of the bar between the handle and the clamping means. According to my invention, said clamping means are constituted by an at least partly annular member surrounding the shank bar and slidingly mounted thereon, the bar engaging the V-shaped bottom of a longitudinal groove in the shank so as to be clamped therein by the clamping member at any desired position of adjustment of said clamping member.

I have illustrated in accompanying drawings two embodiments of such a wrench by way of a mere exemplification.

In said drawings:

Figs. 1 and 2 are two general elevational views of the first embodiment in its inoperative position, in side view and in front view respectively.

Fig. 3 is a transverse section through line 33 of Fig. 2;

Fig. 4 is a plan view of the movable part of the releasing means;

Fig. 5 is a side view of the said releasing means when ready to operate;

Figs. 6 to 11 relate to a second embodiment of the dynamometric wrench;

Fig 6 is a general elevational view of the wrench in the position occupied by it just before operation;

Fig. 7 is a view similar to Fig. 6, the wrench being shown in longitudinal sectional view after operation of the releasing means;

Fig. 8 is a cross-section on a larger scale through line 8'8 of Fig. 6;

Figs. 9 and 10 are a front elevational view and a side View respectively of the stationary retaining projectionforming part of the releasing means;

Fig. 11 is a cross-section of the releasing means through line 11-41 of Fig. 6.

The wrench illustrated in Figs. 1 to 5 includes a rigid cylindrical shank 2 the upper end 3 of which carries a socket or fork adapted to engage a not or a screw to be fastened or released. The lower end of the shank 2 is notched as illustrated so as to form a lateral projecting tongue 4 as best seen in Fig. 2. There is fitted on the shank and at a short distance from its upper end 3 the end of a flexible cylindrical rod 6 of hard steel extending over the left hand side of the shank 2. A longitudinal groove 7 cut in the sidewall of the shank and having a uniform cross-section is engaged by said rod as clearly shown 2,749,786 Patented June 12, 1956 in Fig. 3. The rod 6 projects slightly out of the groove 7 throughout the length of the shank as shown at 6:1 and extends beyond the shank 2 as shown at 6b.

An annular slider 8 enclosing the system constituted by the shank 2 and the rod 6 may slide over a predetermined portion of the length of said system between the securing point 5 for the rod 6 and the free end 4 of the shank 2 and it may be held fast at any predetermined desired point. To this end, the shank 2 carries a scale 9 (Figs. 1 and 2) while the slider 8 is constituted by a ring knurled outwardly and the inner diameter of which is slightly larger than the outer diameter of the shank 2. The annular slider is recessed inwardly along a generating line 8a, its recess matching the boss formed by the projec= tion 6a on the rod 6 engaging the shank 2, said recess merging into the inner periphery of the annular slider, as shown by the curve 8b (Fig. 3).

Consequently, when the inner recess at 8a in the slider registers with the rod 6, said slider may be freely shifted throughout the length of the system 26. But, if at any point of its progression, it is caused to be angularly shifted in the direction of the connecting curve 8b, the latter acts as a cam on the boss constituted by the flange 6a of the rod 6 and urges said rod 6 against the bottom of the groove or fiuting 7 formed in the shank 2.

The slider 8 in effect forms a rigid unit of a more or less considerable length including part of the flexible rod 6 and the shank 2. In other words, if the outer end 6b (Fig. 2) of the rod 6 is submitted to a force that urges it sideways a predetermined distance m (Fig. 5) away from the terminal tongue 4 of the shank 2, said force should increase when the free length of the rod 6 is shorter, i. e. when the slider 8 is nearer the free end 4 of the rigid shank 2.

The arrangement described is associated with releasing means adapted to warn the operator as to the exact moment at which the spacing distance m has been reached so that said operator may put an end at this very moment to the stress exerted by him. These releasing means include a ring 12 adapted to engage the terminal notch of the shank 2 so as to rest on the end of the latter with the tongue 4 on its right hand side (Figs. 2 and 5); said ring 12 may revolve and slide over the flexible rod 6. This ring 12 is made of a single part including in longitudinal sequence:

An annular bead having a triangular cross-section 12a;

A cylindrical section 12b the outer diameter of which is smaller than the outer diameter of the bead 12a;

A wide collar the outer periphery of which is knurled.

The annular bead 12a shows a gap at 12d over a small part of its periphery, the bottom of said gap registering radially with the cylindrical surface of the section 12b as shown in Fig. 5.

The tongue 4 extending alongside of the right hand side of the cylindrical section 12b serves as a carrier for a pointed tool 13, the depth of projection of which is adjusted by the locking nut 13a so that its tip may engage the outside of the cylindrical section 12b of the ring 12. Beyond said ring 12, the flexible rod 6 carries a coil spring 14 and beyond the latter a grip 15 which is secured to it by a screw 16. Consequently, the spring 14 bearing against the grip 15 constantly urges the ring 12 against the end of the shank 2.

The operation of the dynamometric wrench thus described is as follows:

The free length of the flexible rod 6 is adjusted, in accordance with the stress to be transmitted, by shifting the slider 8 over the scale 9. This adjustment being performed, the slider is shifted angularly. Its inner curve 81') acts then as a cam and urges energetically the desired 3 point of the length of the rod 6 against the bottom of the groove 7.

The ring 12 is then caused to be angularly shifted through action on its knurled flange 120 until the gap 12b in the bead 12a registers with the pointed tool 13. The ring 12 is drawn then outwardly towards the handle 15 with a view to stressing the spring 14- and, this being done, the ring 12 is again shifted by a fraction of a revolution until its bead 12a, submitted to the inward action of the spring 14, engages the end of the pointed tool 13. The latter holds now the ring 12 in position against the action of the spring 14. This second operation provides the preliminary setting of the wrench and should be preformed before each fastening operation (Fig. The wrench being positioned over the nut to be fastened, the grip is drawn sideways in order to move the rod 6 out of the shank 2 (Figs. 2 and 5). When the resistance defined by the position of the slider 3 is reached, the free portion of the rod 6 bends and has a tendency to snap away from the tongue of the body 2. Consequently, the pointed tool 13 releases the ring 12, which is urged by the spring 14 against the end of the shank 2 and produces thereby a sharp noise. The operator is thus warned that the desired extent of fastening has been reached.

The pointed tool 13 being adjusted once and for all with reference to the ring 12, it is obvious that, whatever may be the position of the slider 8 and consequently the extent of fastening required for the wrench, the amount of shifting of the grip 15 with reference to the rigid shank 2 is constant.

The second embodiment illustrated in Figs. 6 to 11 is of a similar type, but somewhat improved, wherein the groove 7 in the shank 2, the bottom of which carries the rod 6, assumes a V-shaped outline which constrains said rod 6 to remain always perfectly centered in said groove by reason of the presence of the two surfaces that are symmetrically arranged to either side of the longitudinal plane of symmetry of the groove (Fig. 8).

Furthermore, the slider 8 is provided with a laterally projecting extension 21 forming a cylindrical bore extending perpendicularly to the general axis of the wrench; said bore carrying two auxiliary sliders 22 provided each with a slope 23 engaging either side of the portion of the rod 6 that projects at 6:1 outside the recess or groove 7 in the shank 2. One of said sliders 22 is provided with a smooth hole 24 while the other slider 22 is provided with a tapped hole 25 inside which is screwed a threaded rod 26 carrying a knurled control knob 27, the shoulder 28 on which forms a stop bearing against the rear end of the firstmentioned slider 22 having a smoothhole 24; consequently it is possible to screw said threaded rod 26 into the other slider 22 provided with the tapped opening 25 so as to urge the two sliders together and thereby against the projecting portion 6a of the rod 6. On the other hand, these sliders 22 engage the inner surface of the bore 29 in the extension 21.

Turning to the movable releasable member submitted to the action of the spring 14, it is identical with that illustrated in Figs. 1 to 5. On the other hand, the member engaging or retaining the releasable ring 12, instead of being constituted by a pointed tool 13, is formed by a blade 30 assuming the shape of a knife and secured by a screw 31 to the outer end of the shank 2.

It is thus apparent that, the wrench being in its operative position the spacing or sag shown at m in Fig. 11, even if the direction of stresses exerted on the rod 6 is slightly shifted towards the right hand side or towards the left hand side of the axis of the wrench.

The preliminary setting of the releasing means is performed in the manner disclosed hereinabove with reference to Figs. 1 to 5 by turning the ring 12 so as to bring the gap 12b in the bead 12a into register with the knife 30. The ring 12 may be drawn rearwardly while compressing the spring 14, after which it is turned by a fraction of a revolution so as to bring a section of the projecting annular edge of the bead 12a beyond the knife 30 against which it then abuts as soon as it is urged back by the spring 14.

The release of the ring 12 is provided as soon as the sag assumed by the rod 6 in register with the knife 30 has reached the value m or a slightly greater value.

The ring or slider 8 sliding over the shank 2 carries a screw 32 the tip of which engages a groove 33 provided longitudinally of the shank 2 on the side diametrically opposed to the groove 7 carrying the flexible rod 6, said engagement between the screw 32 and the shank 2 ensuring a more reliable guiding of the slider 8.

Lastly, the rod 6 is advantageously secured to the shank 2 as illustrated in Fig. 7, by means of a shouldered screw 35 passing with a clearance through the rod 6. This arrangement is associated with a sleeve 36 capping the end of said rod and of said shank and adapted to removably carry the actual tool 37, that may be any conventional wrench socket and is provided to this end with a projecting tail-piece 38 extending into said sleeve, which is thus substituted for the stationary tip 3 of Fig. 1.

Obviously and as apparent from the preceding disclosure, the invention is not limited by the sole embodiments described hereinabove and includes all the modifications thereof falling within the scope of accompanying claims.

What I claim is:

1. In a dynamometric wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting outwardly of the periphery of the shank, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, a slider slidably mounted on the rigid shank and engaging the flexible rod at an adjustable point of its length to define on said rod a portion remaining in permanent contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge it away from the shank and thereby move the wrench head in a corresponding direction, and a free portion adapted to be bent away from the rigid shank upon actuation of the hand grip, mechanical means whereby the bending of the free portion of the flexible rod beyond a predetermined distance with reference to the shank produces an audible signal, two wedges assuming slopes of opposite directions, slidingly carried by the slider along a line perpendicular to the axis of the shank and hand-operable means controlling the movement of the wedges towards and away from each other, into and out of engagement with the flexible rod for clamping and releasing the slider at any desired point of its path.

2. In a dynamometric wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided throughout its length with a rectilinear groove, a flexible rod extending along said groove and engaging the surface thereof through at least a part of its length starting from the wrench headand projecting laterally out of said groove to a small extent, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the corresponding point of the shank, the free end of the shank being recessed, meanspermanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, a collar slidably fitted over the system including the shank and the rod, means for clamping the collar at any desired point of its travel over said system to define the part of the flexible rod engaging the groove on one hand and the free end of the flexible rod on the other hand, an annular member slidingly carried by the outer end of the flexible rod on the inside of the hand grip, a spring urging said annular member away from the hand grip towards the first mentioned end of the flexible rod and means carried by the free end of the shank beyond the recess therein and holding normally the annular member in its outer position against the action of said spring and adapted to release said annular member as soon as the flexible rod has been shifted laterally with reference to the shank by a predetermined amount, the annular member when released engaging the recessed section of the rigid shank to produce when impinging thereon an audible signal.

3. In a predetermined torque release wrench, the com bination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting slightly beyond the outline of the shank, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, an at least partly annular member slidingly fitted round the shank and rod system to engage the flexible rod at an adjsutaole point of its length and to define thereby on said rod a portion lying between the securing means and the sliding member and held by the latter in contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge the rod away from the shank and thereby move the wrench head in a corresponding direction, and an outer free portion extending between the sliding member and the grip and adapted to be bent away from the rigid shank upon actuation of the hand grip and means for clamping the sliding member in its selected adjusted position.

4. In a predetermined torque release wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape having a substantially V-shaped bottom, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting slightly beyond the outline of the shank, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, an at least partly annular member slidingly fitted round the shank and rod system to engage the flexible rod at an adjustable point of its length and to define thereby on said rod a portion lying between the securing means and the sliding member and held by the latter in contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge the rod away from the shank and thereby move the wrench head in a corresponding direction, and an outer free portion extending between the sliding memher and the grip and adapted to be bent away from the rigid shank upon actuation of the hand grip and purely mechanical means whereby the bending of the free portion of the flexible rod beyond a predetermined distance with reference to the shank produces in a frictionless manner an audible signal and means for clamping the sliding member in its selected adjusted position.

5. In a predetermined torque release wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting slightly beyond the outline of the shank, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, an at least partly annular member slidingly fitted round the shank and rod system to engage the flexible rod at an adjustable point of its length and to define thereby on said rod a portion lying between the securing means and the sliding member and held by the latter in contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge the rod away from the shank and thereby move the wrench head in a corresponding direction and an outer free portion extending between the sliding member and the grip and adapted to be bent away from the rigid shank upon actuation of the head grip, two wedges assuming slopes of opposite directions, slidingly carried by the sliding member along a line perpendicular to the axis of the shank and hand-operable means controlling the movement of the wedges towards and away from each other, into and out of engagement with the flexible rod for clamping and releasing the sliding member at any desired point of its path.

6. in a predetermined torque release wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape, said shank including a terminal step at its other end, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting slightly beyond the outline of the shank, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the shank, a hand grip rigid with the other end of the flexible rod, an at least partly annular member slidingly fitted round the shank and rod system to engage the flexible rod at an adjustable point of its length and to define thereby on said rod a portion lying between the securing means and the sliding member and held by the latter in contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge the rod away from the shank and thereby move the wrench head in a corresponding direction, and an outer free portion extending between the sliding member and the grip and adapted to be bent away from the rigid shank upon actuation of the head grip, a ring adapted to slide over and turn round the free end of the flexible rod and including a part annular head over its periphery with a gap between the ends of the head, a knife carried by the free end of the rigid shank beyond the step thereon and adapted to retain normally said sliding ring in its outer position through engagement with the inner surface of said bead and to pass through the gap between the ends of said bead for a predetermined angular shifting of the ring, and a spring urging said sliding ring engaged by the knife inwardly as soon as the transverse flexion of the flexible rod has reached a predetermined amount under the action of the stress imparted through the grip to the wrench head and has allowed the bead on the sliding ring to be freely shifted by the spring alongside of the retaining knife, the return of the sliding ring into its inner position producing an audible signal through contact thereof with the knife on the shank.

7. In a predetermined torque release wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and provided with a longitudinal groove of constant cross-sectional size and shape, a flexible rod extending longitudinally inside the groove in the rigid shank and projecting slightly beyond the outline of the shank, a sleeve capping with a slight clearance the cooperating ends of said flexible rod and rigid shank, means for removably and rigidly securing the wrench head to said sleeve, means rigidly and permanently securing the flexible rod and rigid shank to said sleeve, a hand grip rigid with the other end of the flexible rod, an at least partly annular member slidingly fitted round the shank and rod system to engage the flexible rod at an adjustable point of its length and to define thereby on said rod a portion lying between the securing means and the sliding member and held by the latter in contacting relationship with the groove in the rigid shank, whatever stress is imparted to the grip to urge the rod away from the shank and thereby move 7 the wrench head in a corresponding direction, and an outer free portion extending between the sliding member and the grip and adapted to be bent away from the rigid shank upon actuation of the head grip and means for clamping the sliding member in its selected adjusted position.

8. In a predetermined torque release wrench, the combination of a wrench head, a rigid substantially cylindrical shank to one end of which said head is rigidly secured and the free end of which is recessed and provided throughout its length with a rectilinear groove of constant cross-section having two symmetrical sloping elements, a flexible rod extending along said groove and engaging the surface thereof through at least a part of its length starting from the wrench head and projecting laterally out of said groove to a small extent, means permanently and rigidly securing the end of the flexible rod nearest the wrench head to the corresponding point of the shank, a hand grip rigid with the other end of the flexible rod, a collar slidably fitted over the system including the shank and the rod, means for clamping the collar at any desired point of its travel over said system to define the part of the flexible rod engaging the groove on one hand and the free end of the flexible rod on the other hand, an annular member slidingly carried by the outer end of the flexible rod on the inside of the hand grip, a spring urging said annular member away from the hand grip towards the first mentioned end of the flexible rod and means carried by the free end of the shank beyond the recess therein and holding normally the annular member in its outer position against the action of said spring and adapted to release said annular member as soon as the flexible rod has been shifted laterally with reference to the shank by a predetermined amount, said release producing mechanically an audible signal.

References Cited in the file of this patent UNITED STATES PATENTS 2,122,760 Scott et a1 July 5, 1938 2,250,941 Zimmerman July 29, 1941 2,358,461 Latimer Sept. 19, 1944 2,381,226 Parker Aug. 7, 1945 FOREIGN PATENTS 675,755 Germany May 16, 1939 700,320 Germany Dec. 18, 1940 820,275 Germany Nov. 8, 1951 985,565 France Mar. 14, 1951 

